Two differentially regulated Arabidopsis genes define a new branch of the DFR superfamily

Abstract

Two tandem genes were identified on Arabidopsis chromosome II (AtCRL1 and AtCRL2) encoding proteins with homology to members of the dihydroflavonol-4-reductase (DFR) superfamily. The encoded CRL1 and CRL2 proteins share 87% mutual amino acid sequence identity whereas their promoter regions are highly divergent, suggesting differential regulation of the CRL genes. Phylogenetic analysis placed CRL1 and CRL2 in a separate branch of the DFR superfamily. Northern blotting showed strong AtCRL1 induction by abscisic acid (ABA), drought, and heat shock, and high expression level in seeds, thus resembling the expression pattern of late embryogenic abundant ABA-responsive genes. Differential expression of the two genes during plant development was confirmed in plants expressing transcriptional fusions between the two promoters and the Escherichia coli b-glucuronidase reporter gene. This showed that, whereas high expression of AtCRL1 in mature seeds declines during subsequent vegetative growth, transcriptional activity from the AtCRL2 promoter increases during vegetative growth. Expression of both genes is restricted to vascular tissue. Based upon their homology to proteins involved in lignin synthesis, we propose that AtCRL2 is involved in generating conducting tissue late in development, while AtCRL1 is involved in vascular tissue differentiation and/or synthesis in the germinating embryos.

The Basic Leucine Zipper Transcription Factor ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 Is an Important Transcriptional Regulator of Abscisic Acid-Dependent Grape Berry Ripening Processes

“…In addition, VvABF2 seems to affect lignin biosynthesis by the stimulation of CAD and laccase genes (Tables III and IV). The induction of lignin biosynthetic genes by ABA was previously illustrated in Arabidopsis (Østergaard et al, 2001;Seki et al, 2002) Finally, several reports indicate that fruit softening is hormonally regulated by ABA and ethylene (Jiang et al, 2000;Zhang et al, 2009aZhang et al, , 2009b. Inhibitors of ABA biosynthesis delay tomato ripening and softening (Zhang et al, 2009a(Zhang et al, , 2009b.…”

Molecular Cloning and Characterization of Three Genes Encoding Dihydroflavonol-4-Reductase from Ginkgo biloba in Anthocyanin Biosynthetic Pathway

“…found proteins encoded by the CRL1 and CRL2 genes located on chromosome 2 of Arabidopsis thaliana that are highly homologous to the DFR superfamily. CRL1 and CRL2 belong to a separate branch of the DFR superfamily phylogenetically [39]. The phylogenetic tree indicated that Asn-type DFRs are widely distributed in plants, that and DFRs in monocotyledons are all Asn-type, while Asp-type DFRs are only distributed in some dicotyledons.…”

Dihydroflavonol 4-Reductase Genes from Freesia hybrida Play Important and Partially Overlapping Roles in the Biosynthesis of Flavonoids

“…Variable DFR –like gene numbers were therefore found in various genomes, e.g., a single copy DFR is present in Arabidopsis thaliana , in which the anthocyanin and proanthocyanidin components seemed to be simple as well, while multicopy DFR genes exist in M. truncatula, L. japonicus, Populus trichocarpa , and F. hybrida , these metabolites showed more complicated patterns and more diverse physiological functions (Østergaard et al, 2001; Xie et al, 2004; Shimada et al, 2005; Huang et al, 2012). Susumu Ohno hypothesized that gene duplication drives the evolution of novel functions, and deduced three kind fates of the duplicated genes: silence, neofunctionalization and subfunctionalization (Epstein, 1971).…”